This invention relates to the art of electrical connectors which include a means for detecting and indicating proper grounding of an electrical device.
Various types of electrical connectors with ground fault detectors are known. These connectors incorporate rudimentary detector circuits generally including only a resistor and/or diode and a neon lamp. One type includes a detector circuit and indicator lamp mounted on a separate plate or body which establishes electrical contact intermediate various portions of the connection such as between a plug and a wall socket. Connectors and indicators of this type are described in U.S. Pat. Nos. 2,449,150 and 3,753,261.
Another type of ground fault and circuit continuity detector comprises a plug to be received within a receptacle which provides only means for indication of proper contact and grounding of the receptacle rather than acting as an electrical connector for an external device. Detectors of this type are described in U.S. Pat. Nos. 2,997,701; 3,383,588; and 4,166,242.
A third type comprises an electrical connector in which a ground fault detector and indicator circuit is incorporated directly into the electrical connector. Electrical contact is made between the various portions of the electrical connector and a circuit to provide a visual indication of proper connection and grounding. This type of connector may also incorporate means for disconnecting circuit continuity when proper connection and grounding is not effected. Visual indication is provided by a lamp mounted on the exterior of the connector body. Thus, the visual indication is provided in a directional manner which may be shielded from view by connector orientation or other external physical obstructions near the connectors. Connectors of this type are described in U.S. Pat. Nos. 3,171,113; 3,659,152; 3,873,951; and 3,924,914.
The present invention provides a new and improved electrical connector with ground fault detector. In accordance with the invention, the electrical connector comprises a housing including means for establishing electrical connection such as with contact blades in a plug or receptable contacts in a socket. A conductor cable extends within the housing and connected to the contact means and an integral, modular ground fault detector circuit and indicator mounted within the housing. The housing includes a plurality of radially disposed windows which are adjacent the indicator to provide a circumferential visual indication of the properly connected contact circuitry.
As used in this specification, the term "ground fault detector" will be understood to include detectors for sensing improper connection of the "hot" and "neutral" leads of an electrical circuit as well as fault in the ground connection.
Further in accordance with the invention, the ground fault detector and indicator circuitry is incorporated in a modular unit which is easily mounted within the housing and is readily replaceable in the event of failure. Advantageously, the electrical connection between the connector and the ground fault detector circuitry is established through a resilient contact means so that replacement of a defective ground fault detector module is easily effected without the necessity of time consuming assembly procedures such as soldering. It is thus unnecessary to dispose of the entire electrical connector if there is merely a failure of the detector circuit.